After the ultra-low emission transformation

the contaminants emission limits of coal-fired power plants are reduced hugely and the statuses of emission reduction equipment are getting worse simultaneously. Hence

new operation problems have appeared in the flue gas purification equipment. Crystallization problem has taken place in the flue system of some coal-fired power plants

such as on the surface of bag filter clean room

induced draft fan hub

FGD inlet flue and so on. The results of the crystal analysis show that the main component of crystalline is ammonium chloride

which is up to 90%. In this study

the crystallization reaction mechanism of ammonium chloride was studied and calculated. The results show that the crystallization temperature of ammonium chloride is about 75-115 °C. Therefore

the crystallization problems of ammonium chloride could be found in the dust separator

induced draft fan and GGH. The crystallization of ammonium chloride could not only clog the equipment

but also corrode the surfaces of the flue system. According to the actual operation situation

some prevention and control measures are proposed. And this paper suggested to reduce the concentrations of ammonia and hydrogen chloride in the flue gas to avoid the crystallization problem of ammonium chloride.